The present invention is related to a power supply system, and more particularly, to a power supply system with AC redundant power sources and a safety device to provide auxiliary AC electric power to operate the DC power supplies of the power supply system when the AC power source in operation is abnormally interrupted, and to provide a safety device to prevent the AC power sources of the power supply system from getting short-circuited caused by the inlet of the power supply system being plugged into the outlet of the AC power source in an inverse direction.
The contemporary power supply system with DC (direct current) redundant power supplies is depicted in FIG. 1. The power supply system with DC redundant power supplies includes a single AC (alternating current) power source 11 provided to supply AC electric power to operate a plurality of DC power supplies 12, 13, and 14 which are connected in parallel for outputting combined DC electric power. The configuration of the contemporary power supply system with DC redundant power supplies is advantageous over the situation that if one of DC power supplies which is designated to supply DC electric power in normal operation is failed, the other DC power supplies can supply DC electric power without interruption.
Despite the advantages of the contemporary power supply system, assuming that the single AC power source 11 is abnormally interrupted in supplying AC electric power to operate the DC power supplies 12, 13, and 14, the operation of the whole power supply system will halt and the power supply system will come into power outage. As a rule, an ideal power supply system must includes not only the functionality of providing auxiliary DC power supplies, but also includes the functionality of providing auxiliary AC power sources to supply AC electric power to operate the DC power supplies in case the AC power source in operation is abnormally interrupted.
At present, the implementation of the outlet of the AC power source is roughly falls into a two hole outlet and a three hole outlet, and most of the outlet of the AC power source is provided with a foolproof contrivance. The foolproof contrivance is used to allow the inlet of the power supply system to be able to plug into the outlet of the AC power source in a specific direction, in order that the inlet of the power supply system can acquire a fixed live line and an earth line from the AC power source. Nonetheless, in some situations the inlet of the power supply system can be plugged into the outlet of the AC power source in an inverse direction, for example, the outlet of the AC power source is not provided with a foolproof contrivance. This would cause the AC power source of the power supply system short-circuited.
It is inclined to provide a power system with AC redundant power sources and a safety device, to assure that the power system can sustain supplying electric power in event that the AC power source in operation is abnormally interrupted, and prevent the AC power sources from getting short-circuited caused by the inlet of the power supply system being plugged into the outlet of the AC power source of the power supply system in an inverse direction.
According to a preferred embodiment of the present invention, the power supply system is arranged to include three DC power supplies which are connected in parallel for outputting a combined DC power output, two AC power sources, each of the AC power sources is directly coupled in series with a corresponding one of the DC power supplies to provide an AC voltage to operate the corresponding one of DC power supplies, a control circuit coupled between the AC power sources and the DC power supply which is not directly coupled in series with a corresponding one of AC power sources for creating a conductive path to transfer the AC voltage from one of the AC power sources to the DC power supply which is not directly coupled in series with a corresponding one of AC power sources when the other AC power source is abnormally interrupted in supplying an AC voltage to operate the DC power supplies, wherein the control circuit includes a safety device for preventing the AC power sources from getting short-circuited.
The control circuit may further comprises a first switch circuit coupled in series with one of the AC power sources for receiving an AC voltage from one of the AC power sources and transmitting the AC voltage to the safety device, a second switch circuit coupled in series with one of the AC power sources for receiving an AC voltage from one of the AC power source and transmitting the AC voltage to the safety device, and a voltage transfer circuit which is coupled with the safety device and the DC power supply which is not directly coupled in series with one of the AC power sources for alternatively creating a conductive path in response to a control signal to provide either the AC voltage being transferred from the first switch circuit or the AC voltage being transferred from the second switch circuit to the DC power supply coupled therewith.
Both of the above-described first switch circuit and the second switch circuit are implemented by two serially-connected relays, and the voltage transfer circuit is implemented by two two-to-one relays. Both of the first switch circuit and the second switch circuit are operable to isolate the interrupted power source from the power source in operation to protect one from getting electric shock when one touches the interrupted AC power source. The abovementioned safety device may comprise a first full wave rectifier coupled with the first switch circuit and one of the two-to-one relay of the voltage transfer circuit for rectifying the AC voltage being transferred from the first switch circuit and a second full wave rectifier coupled with the second switch circuit and the other one of the two-to-one relay of the voltage transfer circuit for rectifying the AC voltage being transferred from the second switch circuit. Moreover, the control circuit for creating a conductive path for transferring the AC voltage from one of the AC power sources to the DC power supply which is not directly coupled in series with the AC power sources further includes a microprocessor, which persistently detects the AC voltages from each of the AC power sources and generate a control signal to drive the voltage transfer circuit to create a conductive path to transfer an AC voltage from one of the AC power sources to the DC power supply which is coupled with a corresponding voltage transfer circuit when the other AC power source is interrupted in supplying an AC voltage to operate the DC power supplies. When the interrupted AC power source becomes normal, the microprocessor can generate a control signal to restore the conductive path between the interrupted AC power and the corresponding DC power supply.
Broadly speaking, the number of the DC power supplies of the power supply system in accordance with the present invention can be indicated in terms of 2N+1, wherein N is a positive integer number, and the number of the voltage transfer circuits should be identical to the number of the DC power supplies each of which is coupled with a corresponding voltage transfer circuit.
Now the foregoing and other features and advantages of the present invention will be more clearly understood through the following descriptions with reference to the drawings, wherein: